Technique of Integral Assessment of Long-term Variations of Streamflow Quality by the Example of the Vorskla River

E. A. Rumyantseva and N. N. Bobrovitskaya

Athree-stage technique of complex assessment of long-term polluted streamflow variations and their formation factors is proposed. The first stage comprises automated calculations of relative intra-annual duration and volume of polluted water flow for each ingredient and each year of the whole period under study from limiting indicators. The calculation program is based on the major theses on these integral indicators developed earlier at the State Hydrologic Institute. In the second stage, assessment of long-term variations of calculated indicators and their formation factors is carried out using the principal component method, that gives an idea of conventionally representative indicators of polluted flow. In the third stage, long-term tendencies of relative volume of polluted water flow for conventionally representative indicators are assessed. Informativeness of assessments is demonstrated by the example of the Vorskla River crossing the Russian-Ukrainian boundary.